Alternate picking: wrist placement?

Until now, i've always had my wrist kindof resting on either an unused string, or the bridge, or the guitar. Today i figured out it i float my wrist (without anchoring my pinky) its easilr to pick faster, and sounds more fluent. but the problem is it feels uncoordinated, and it tires out my arm pretty bad. so is this the PROPER way to alternate pick, or most widely used in shred? or should this be something i shouldn't persue?